Patent GB-237929-A (GB)
Title: Improvements relating to the formation of piles
IPC: E02D5/36
Filed: 1925-08-04
Abstract: 237,929. Rotinoff, A. G. Aug. 4, 1924, [Convention date]. Piles.-Piles are constructed in situ by forming a hole and forcing filling material into the hole simultaneously by means of a tool 1, Fig. 1, formed with a screw-thread 9. A shoe 2 may be loosely connected to the lower end of the tool so as to be driven down therewith. The tool passes through a. collar around which is a hopper 4 into which concrete is fed by a shoot 5. The tool 1 is attached to a driving head 11 provided with a wooden dolly 12 and carried in a collar 14 having sliding members engaging guides on the pile-driving derrick. The driving monkey 13 acts on the dolly 12. The driving head 11 is provided with a bevel gear 18 adapted to be rotated by means of a bevel pinion driven through reduction gearing from an electric motor 22 mounted on a projecting part of the collar 14. Before and during driving, the hopper 4 is supplied with concrete, which is carried down by the screw 9 and fills the hole formed by the tool 1 and shoe 2. The tool may be rotated at the same time, so as consolidate the concrete, or it may be rotated only as it is withdrawn. The concrete may be consolidated by partially withdrawing the tool and then delivering a few blows by the monkey 13. In withdrawing, the tool 1 may be weighted to increase the downward pressure on the concrete, but withdrawal is facilitated and sufficient consolidation obtained by counterbalancing the tool by a counterpoise exerting a constant upward pull thereon. Reinforcement 27 consisting of steel bars, expanded metal or wire framework may be attached to the shoe. In a modification for producing tapered piles, the tool 1, Fig. 6, is provided with a tapered screw 29 preferably having its lower edge 30 bevelled. A shoe 31 may be used, but piles may be produced without using such a shoe. In a further modification a thin metal shell 32, Fig. 8, preferably provided with a helical groove 34 fits over the tapered screw 33 of the driving tool 1. The tool is provided with a bore 35 through which concrete or cement mixture is supplied under pressure during driving. Preferably a shoe 37 is used, and the tool 1 is provided with passages at the bore 35 to the outside of the shell 32. Concrete is also supplied to the hopper 4 and is carried down by the shell 32, so that a concrete pile having the shell embedded therein is produced. The tool 1 is removed by unscrewing for & few turns and then lifting vertically. A tool 1, Fig. 10, having a short screw-thread 40 of a maximum diameter slightly less than that of the finished pile may be used, together with a thin metal shoe 41. This tool is suitable for the production of piles having enlargements, by partly withdrawing the tool and applying downward pressure thereto so as to force the concrete outwards. For this purpose the lower face of the screw-thread 40 is sloped upwardly and outwardly. Piles may be driven through a stratum of water by extending the hopper 4, Figs. 1, 6, and 8, or the ring 8 through the water. In dry soils. the method may be used to form piles of sand or gravel, or composite, piles having a lower part of sand or gravel and an upper part of concrete.